1. Technical Field
This invention relates generally to an internal combustion engine having two pistons disposed in a common cylinder, and more particularly to such an engine having three combustion chambers in each cylinder of the engine.
2. History of Related Art
Several arrangements have been proposed for internal combustion engines having two double-acting pistons mounted in a common cylinder. In this type of engine, a combustion chamber is provided between each piston and an adjacent cylinder head, and in some arrangements also between the two pistons, thereby providing three combustion chambers per cylinder.
For example, U.S. Pat. No. 2,203,648 issued Jun. 4, 1940 to F. C. Dons describes a two-stroke engine having three combustion chambers formed between, and at the outer ends, of two pistons disposed in a single cylinder. U.S. Pat. No. 2,388,756 granted Nov. 13, 1945 to W. G. Meyers likewise discloses an engine, operating in a two-stroke cycle, with double-acting pistons mounted in a common cylinder. U.S. Pat. No. 2,532,106, issued Nov. 28, 1950 to Theodore Korsgren also describes a two-stroke cycle opposed piston engine having three combustion chambers in each cylinder. Another example of an opposed piston engine, capable of operating in either a two or four-stroke cycle mode is described in U.S. Pat. No. 3,010,440 granted Nov. 28, 1961 to A. Roth.
All of the combustion chambers in each of the above-referenced engines operate contemporaneously in a common, i.e., the same, combustion mode using a predesignated fuel source. Thus, when optimizing engine performance, each of the above-referenced engines are limited to certain advantages provided by the particular operating cycle. For example, the four-stroke cycle has advantages in some operational areas over the two-stroke cycle, such as easier power regulation over wider variations in speed and load, cooler pistons, no fuel loss during exhaust, lower specific fuel consumption, and lower hydrocarbon emissions. The two-stroke cycle advantages, compared with four-cycle engines, include a 50% to 80% greater power output per unit piston displacement at the same speed and twice as many power impulses per crankshaft rotation.
The present invention is directed to overcoming one or more of the problems and limitations inherent in previous opposed piston engines.